Overall, some 8 per cent of voters remain undecided. Among women, however, an increasing number are coming down in favour of voting No.

The results show that the No campaign now has a 16 point lead among women who have decided which way to vote - up from 14 points on Sunday. Some 58 per cent of women say they will vote No on Thursday, with 42 per cent planning to vote Yes, among those who have reached a decision.

Men are more evenly split but more than half – 53 per cent – now back independence.

The findings come as Alex Salmond, Scotland’s first minister and leader of the Yes campaign, and Alistair Darling, the leader of the pro-Union Better Together campaign, embark on a last frantic effort to win over undecided voters.

Turn-out is widely predicted to break records, with 4.3 million voters registered to take part.

The Telegraph/Opinium poll found 91 per cent of respondents said they were certain to vote. Only one per cent said they would definitely not vote in the referendum.

The poll was conducted online among Scottish adults over the age of 16 – who have a vote in the Scottish referendum - between last Friday and Monday. It found:

:: Among all respondents, 43 per cent are set to vote Yes, 47 per cent No, eight per cent don’t know and one per cent say they will definitely not vote. When undecided voters are excluded, 48 per cent said they will vote Yes to independence, with 52 per cent saying they will vote No.

:: Half of Scots think the referendum battle has caused deep divisions within Scotland and damaged relations with the rest of the UK. Only 23 per cent believe that the campaign has been “a force for good” that has brought Scots closer together.

:: Mistrust of Westminster politicians seems to be a significant factor in the support for independence. Half of all voters and 85 per cent of Yes supporters simply do not believe the promise of more devolution from David Cameron, Ed Miliband, Nick Clegg and Gordon Brown.

:: If Scotland votes in favour of independence, respondents believe the main driving force will have been “dislike” of Westminster politicians, a factor named by 38 per cent. The next most popular reason for supporting independence was “a sense of Scottish national pride”, named as the most influential factor by 18 per cent of voters.

The Prime Minister has struggled to win support for the Conservatives among women voters.

Now, women in Scotland appear to hold the key to the outcome of the referendum, and Mr Cameron’s own future, in their hands.

James Endersby, managing director of Opinium Research, said “the referendum remains on a knife-edge” and women voters, with the over-55s, were putting the No campaign “narrowly ahead”.

“No has a 16 point lead among women and a 24 point lead among the over 55’s,” he said. “Yes is narrowly ahead among men and those aged 54 and under.”

Some senior Conservatives at Westminster are said to be dismayed that a complacent Downing Street operation has failed to engage with the threat to the UK from Scottish independence until it is too late.

One former minister is reported to have said: “It’s essay crisis politics. The whole thing has been a complete shambles.”

The poll underlined the extent of Scottish voters’ alienation from Westminster politics.

Mr Salmond is significantly more trusted than any of the Westminster politicians in the referendum debate. The No campaign’s most trusted figure is Gordon Brown.

:: Opinium Research carried out an online survey of 1,156 adults in Scotland aged 16+ from 12th to 15th of September 2014. Results have been weighted to nationally representative criteria. Full tables and results are available here.